Direct digital signal processor control of multi-channel scan for re-establishing connections in a wirelessly networked device
Summary by NHIP
DSP-Controlled Channel Scanning
The method uses a digital signal processor to scan wireless broadcast channels while a main processor remains in low power mode. The DSP compares received signal strength against a threshold, wakes the main processor upon finding an acceptable channel, and returns to a lower power sleep mode between scanning cycles.
Claim Score by NHIP
Abstract
A method and system for establishing a wireless connection between a portable computer system and a wireless network, particularly when the portable computer system goes out of coverage and a wireless connection needs to be re-established. The portable computer system has a main processor and a digital signal processor (DSP). The main processor is placed in a low power mode, conserving battery power. When the portable computer system goes out of coverage, broadcast channels used by the wireless network are scanned by the DSP instead of the main processor to identify channels that have sufficient signal strength for the wireless connection. Thus, the main processor remains in the low power mode. When the DSP identifies acceptable channels, it wakes up the main processor and identifies the channels having sufficient signal strength. The main processor then establishes a wireless connection using one of the channels identified by the DSP.

Term
Term ended
Expired 12 March 2023, 3.5 years ago.
- Priority and filed
- Granted
- Expired
- Today
23 claims: 3 independent, 20 dependent
- 1Broadest claimClaim Score 55, average(NHIP)In a portable computer system comprising a digital signal processor (DSP) and a main processor, a method for establishing a wireless connection between said portable computer system and a wireless network, said method comprising:scanning a plurality of broadcast channels used by said wireless network, wherein said scanning is performed under direction of said DSP while said main processor remains in said low power mode;determining whether a broadcast channel is acceptable for said wireless connection, wherein said determining is executed by said DSP while said main processor remains in said low power mode;said DSP waking up said main processor provided a broadcast channel acceptable for said wireless connection is identified and otherwise said DSP repeating said scanning at periodic time intervals until said broadcast channel acceptable for said wireless connection is identified, wherein said DSP is placed in a lower power sleep mode between each said scanning;and said DSP identifying to said main processor said broadcast channel acceptable for said wireless connection.
- 9A portable computer system comprising:a bus;a wireless transceiver coupled to said bus;a main processor coupled to said bus;and a digital signal processor (DSP) coupled to said bus, said DSP for executing a method for establishing a wireless connection between said portable computer system and a wireless network, said method comprising: scanning a plurality of broadcast channels used by said wireless network, wherein said scanning is performed while said main processor is in a low power mode;determining whether a broadcast channel is acceptable for said wireless connection, wherein said determining is executed while said main processor remains in said low power mode;waking up said main processor provided a broadcast channel acceptable for said wireless connection is identified and otherwise said DSP repeating said scanning at periodic time intervals until said broadcast channel acceptable for said wireless connection is identified, wherein said DSP is placed in a lower power sleep mode between each said scanning;and identifying to said main processor said broadcast channel acceptable for said wireless connection.
- 17In a portable computer system comprising a digital signal processor (DSP) and a main processor, a method for establishing a wireless connection between said portable computer system and a wireless network, said method comprising:scanning a plurality of broadcast channels used by said wireless network, wherein said step of scanning is performed under direction of said DSP while said main processor is in a low power mode and wherein said step of scanning is automatically initiated in response to a triggering event;said DSP comparing to a threshold value a measure of signal strength of each signal received over said plurality of broadcast channels, wherein said threshold is for defining a signal strength acceptable for said wireless connection;said DSP waking up said main processor provided a broadcast channel acceptable for said wireless connection is identified, and otherwise said DSP repeating said scanning until a broadcast channel acceptable for said wireless connection is identified, wherein said DSP is placed in a lower power sleep mode between each said scanning;and said DSP identifying to said main processor said broadcast channel acceptable for said wireless connection.
Independent claims3
60 paragraphs in 4 sections, as filed
BACKGROUND OF THE INVENTION
00011. Field of the Invention
0002The present invention relates to the field of portable computer systems, such as personal digital assistants or palmtop computer systems. Specifically, the present invention relates to a portable computer system with wireless (radio) communication capability.
00032. Related Art
0004A portable computer system, such as a personal digital assistant (PDA) or palmtop, is a computer that is small enough to be held in the hand of a user and is thus “palm-sized.” By virtue of their size, portable computer systems are lightweight and so are exceptionally portable and convenient.
0005Portable computer systems are generally powered using either rechargeable or disposable batteries. Because of the desire to reduce the size and weight of the portable computer system to the extent practical, smaller batteries are used. Thus, power conservation in portable computer systems is an important consideration in order to reduce the frequency at which the batteries either need to be recharged or replaced. Consequently, the portable computer system is placed into a low power mode (e.g., a sleep mode or deep sleep mode) when it is not actively performing a particular function or operation.
0006Some portable computer systems are equipped with radio transmitters and receivers (transceivers) that provide the capability for two-way communication between the portable computer system and a wireless communications network. Accordingly, in addition to the main processor, the portable computer system may include a digital signal processor (DSP) for processing data to be transmitted or data that are received via the transceiver.
0007In the past, when communication occurred between the portable computer system and the wireless network, the portable computer system knew when to expect a transmission. For example, when information or data were being wirelessly transmitted to the portable computer system, it was usually in response to a request initiated by the portable computer system. Thus, the portable computer system was deliberately placed in a receiving mode when a transmission was anticipated, and usually was not in a receiving mode otherwise.
0008The sophistication of portable computer systems has increased, and therefore portable computer systems are frequently used in applications in which they need to be ready to receive transmitted information at any time, similar to the way a cellular telephone operates. For example, when a cellular telephone is powered on, it is ready to receive an incoming call at any time. Similarly, a portable computer system is ready to receive information at any time that the transceiver is powered on, even if other parts of the portable computer system are in a sleep (low power) mode. Generally, devices transmitting information to the portable computer system have the expectation that the portable computer system will be in a mode in which it can receive the information.
0009Accordingly, it is desirable for the portable computer system (with a wireless transceiver) to remain “in coverage” when the transceiver is on; that is, it should have a persistent wireless connection to the network. However, due to its portability, there may be occasions in which the portable computer system is moved “out of coverage.” For instance, while in one location, the portable computer system may have established a wireless connection over a particular broadcast channel used by the network. After moving to a different location, a signal over that channel may be too weak, and consequently the connection over that channel may be lost.
0010Currently, when the transceiver is on and the portable computer system moves out of coverage, the portable computer system will attempt to re-establish a wireless connection to the network over a different channel. Often, as described above, the portable computer system may be in a low power mode. Consequently, in order to re-establish connection with the network, the main processor needs to awaken from the low power mode. The main processor then implements a routine to scan for available channels, to select a channel, and to establish a connection over the selected channel.
0011However, waking up the main processor is problematic because it can consume a significant amount of power, which is inconsistent with the desire to reduce power consumption and conserve the life of the battery. Accordingly, what is needed is a method and/or system that can be used for reestablishing a wireless connection when an existing connection is lost and that can reduce the amount of power needed to do so. The present invention provides a novel solution to these needs.
SUMMARY OF THE INVENTION
0012The present invention provides a method and system that can be used for re-establishing a wireless connection when an existing connection is lost while reducing the amount of power needed to do so. The present invention provides these advantages and others not specifically mentioned above but described in the sections to follow.
0013The present invention pertains to a method and system for establishing a wireless connection between a portable computer system and a wireless network. In one embodiment, the wireless network is a Mobitex wireless communication system. The present invention can be implemented when the portable computer system goes out of coverage and a wireless connection needs to be re-established. The present invention can also be implemented when the portable computer system is powered on (at startup) and a broadcast channel cannot be acquired.
0014In one embodiment of the present invention, the portable computer system has a main processor and a digital signal processor (DSP). The main processor is placed in a low power mode, conserving battery power. When an established wireless connection between the portable computer system and the wireless network is lost (e.g., when the portable computer system goes “out of coverage”), broadcast channels used by the wireless network are scanned under direction of the DSP instead of the main processor. From the scan, the DSP can identify channels that have signal strength sufficient for re-establishing the wireless connection. Thus, the main processor remains in the low power mode while the DSP implements a search for an acceptable channel.
0015When the DSP identifies one or more acceptable channels, it wakes up the main processor and identifies to the main processor the channels having sufficient signal strength. The main processor then establishes a wireless connection using one of the channels identified by the DSP. When the DSP cannot find an acceptable channel, it repeats the search at periodic intervals until an acceptable channel is identified.
0016In one embodiment, the DSP compares the signal strength of each channel to a threshold value in order to compile a list of those channels with a signal strength that is acceptable for a wireless connection. In another embodiment, when multiple acceptable channels are identified by the DSP, the DSP sorts (ranks) the channels according to their respective signal strength. In either embodiment, the main processor is then awakened and establishes a wireless connection with the wireless network, typically using the channel with the highest signal strength.
0017In one embodiment, certain channels used by the wireless network are disregarded by the DSP. For example, certain channels may not be scanned, or signals received over those channels may be ignored. Thus, channels known to have a lot of noise, or channels that are not suitable for a wireless connection for some other reason, will not cause the processor to be unnecessarily awakened.
0018Thus, in accordance with the present invention, the DSP implements a process for performing multi-channel scans without waking the main processor. Therefore, only the DSP needs to stay up to direct the scans. Not until the DSP determines that the portable computer system can be placed into coverage, or the user tries to perform an over-the-air operation manually, is the main processor awakened. This stops the deep sleep process and returns control to the protocol stack in the main processor. The main processor can then establish the wireless connection and place the portable computer system back into the in-coverage mode of operation. With the main processor remaining in a low power mode while the DSP performs the multi-channel scan, power is conserved and battery life is prolonged (that is, batteries do not have to changed or charged as frequently).
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:
<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram of an exemplary network environment including a portable computer system in accordance with one embodiment of the present invention.
<figref idref="DRAWINGS">FIG. 2</figref> is a top side perspective view of a portable computer system in accordance with one embodiment of the present invention.
<figref idref="DRAWINGS">FIG. 3</figref> is a bottom side perspective view of the portable computer system of FIG. <b>2</b>.
<figref idref="DRAWINGS">FIG. 4</figref> is a block diagram of an exemplary portable computer system upon which embodiments of the present invention may be practiced.
<figref idref="DRAWINGS">FIG. 5</figref> is a flowchart showing the steps in a process for establishing a wireless connection between a portable computer system and a wireless network in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
0025In the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one skilled in the art that the present invention may be practiced without these specific details or with equivalents thereof. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.
0026Notation and Nomenclature
0027Some portions of the detailed descriptions, which follow, are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed on computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, computer executed step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.
0028It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present invention, discussions utilizing terms such as “scanning” or “determining” or “waking” or “identifying” or “comparing” or “sorting” or “selecting” or “establishing” or “disregarding” or “initiating” or the like, refer to the action and processes of a computer system (e.g., process <b>500</b> of FIG. <b>5</b>), or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.
0029Exemplary Palmtop Platform
0030<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram of an exemplary network environment <b>50</b> including a portable computer system <b>100</b> in accordance with one embodiment of the present invention. Portable computer system <b>100</b> is also known as a palmtop or palm-sized computer system, a hand-held device, a personal digital assistant (PDA), or a personal information device (PID). In one embodiment, portable computer system <b>100</b> has the ability to transmit and receive data and information over a wireless communication interface (e.g., a radio interface).
0031In the present embodiment, base station <b>32</b> is both a transmitter and receiver base station, which can be implemented by coupling it into an existing public telephone network <b>34</b>. Implemented in this manner, base station <b>32</b> enables portable computer system <b>100</b> to communicate with a proxy server computer system <b>36</b>, which is coupled by wire to the existing public telephone network <b>34</b>.
0032Furthermore, proxy server computer system <b>36</b> is coupled to the Internet <b>52</b>, thereby enabling portable computer system <b>100</b> to communicate with the Internet <b>52</b>. Coupled with Internet <b>52</b> are multiple computer systems (e.g., servers) exemplified by computer system <b>30</b>. When communicating with a Web site over Internet <b>52</b>, protocols such as CTP (Compact Transport Protocol) and CML (Compact Markup Language) can be used by portable computer system <b>100</b> in the present embodiment.
0033It should be appreciated that within the present embodiment, one of the functions of proxy server <b>36</b> is to perform operations over the Internet <b>52</b> on behalf of portable computer system <b>100</b>. For example, proxy server <b>36</b> has a particular Internet address and acts as a proxy device for portable computer system <b>100</b> over the Internet <b>52</b>.
0034It should be further appreciated that other embodiments of a communications network, planned or envisioned, may be utilized in accordance with the present invention. For example, a wireless connection may be made from portable computer system <b>100</b> either directly to the Internet <b>52</b> or directly to computer system <b>30</b>. It is also appreciated that portable computer system <b>100</b> may be coupled to computer system networks other than the Internet <b>52</b>, such as an Intranet, local area network, or the like.
0035The data and information that are communicated between base station <b>32</b> and portable computer system <b>100</b> are the same type of information and data that can conventionally be transferred and received over a wireless communication interface. It should be appreciated that one embodiment of a wireless communication system in accordance with the present invention is the Mobitex wireless communication system.
0036<figref idref="DRAWINGS">FIG. 2</figref> is a perspective illustration of the top face <b>100</b><i>a </i>of one embodiment of the portable computer system <b>100</b> of the present invention. The top face <b>100</b><i>a </i>contains a display screen <b>105</b> surrounded by a bezel or cover. A removable stylus <b>80</b> is also shown. The display screen <b>105</b> is a touch screen able to register contact between the screen and the tip of the stylus <b>80</b>. The stylus <b>80</b> can be of any material to make contact with the screen <b>105</b>. The top face <b>100</b><i>a </i>also contains one or more dedicated and/or programmable buttons <b>75</b> for selecting information and causing the computer system to implement functions. The on/off button <b>95</b> is also shown.
0037<figref idref="DRAWINGS">FIG. 2</figref> also illustrates a handwriting recognition pad or “digitizer” containing two regions <b>106</b><i>a </i>and <b>106</b><i>b</i>. Region <b>106</b><i>a </i>is for the drawing of alphabetic characters therein (and not for numeric characters) for automatic recognition, and region <b>106</b><i>b </i>is for the drawing of numeric characters therein (and not for alphabetic characters) for automatic recognition. The stylus <b>80</b> is used for stroking a character within one of the regions <b>106</b><i>a </i>and <b>106</b><i>b</i>. The stroke information is then fed to an internal processor for automatic character recognition. Once characters are recognized, they are typically displayed on the screen <b>105</b> for verification and/or modification.
0038<figref idref="DRAWINGS">FIG. 3</figref> illustrates the bottom side <b>100</b><i>b </i>of one embodiment of the palmtop computer system that can be used in accordance with various embodiments of the present invention. An extendible antenna <b>85</b> is shown, and also a battery storage compartment door <b>90</b> is shown. A serial port <b>180</b> and an infrared port <b>64</b> are also shown. In one embodiment, infrared communication mechanism <b>64</b> is compliant with the IrDA (Infrared Data Association) standard and protocol.
0039<figref idref="DRAWINGS">FIG. 4</figref> is a block diagram of one embodiment of a portable computer system <b>100</b> upon which embodiments of the present invention may be implemented. Portable computer system <b>100</b> is also often referred to as a PDA, a PID, a palmtop, or a hand-held computer system.
0040Portable computer system <b>100</b> includes an address/data bus <b>300</b> for communicating information, a central (main) processor <b>450</b> coupled with the bus <b>300</b> for processing information and instructions, a volatile memory <b>410</b> (e.g., random access memory, RAM) coupled with the bus <b>300</b> for storing information and instructions for the main processor <b>450</b>, and a non-volatile memory <b>430</b> (e.g., read only memory, ROM) coupled with the bus <b>300</b> for storing static information and instructions for the main processor <b>450</b>. Portable computer system <b>100</b> also includes an optional data storage device <b>490</b> (e.g., a memory stick) coupled with the bus <b>300</b> for storing information and instructions. Device <b>490</b> can be removable. Portable computer system <b>100</b> also contains a display device <b>105</b> coupled to the bus <b>300</b> for displaying information to the computer user.
0041In the present embodiment, portable computer system <b>100</b> includes a transceiver <b>408</b> providing it with the capability for wireless communication. The transceiver <b>408</b> provides a wireless radio frequency (RF) communication link between computer system <b>100</b> and other devices, using any of the various RF protocols and standards. In one embodiment, the Mobitex wireless communication specification is used. It is appreciated that transceiver <b>408</b> may be integrated into portable computer system <b>100</b>, or that transceiver <b>408</b> may be a separate component coupled to portable computer system using, for example, serial port <b>180</b>.
0042It is appreciated that in another embodiment portable computer system <b>100</b> may also include a telephony chipset or the like providing it with the functionality of a cellular phone, in particular the capability to transmit and receive cellular communications. In one embodiment, the telephony chipset is compatible with the standards for GSM and GPRS (Global System for Mobile Communications and General Packet Radio Service, respectively). It is appreciated that other telephony protocols and standards may also be used with the present invention.
0043In the present embodiment, portable computer system <b>100</b> of <figref idref="DRAWINGS">FIG. 4</figref> includes communication circuitry <b>420</b> coupled to bus <b>300</b>. In one embodiment, communication circuitry <b>420</b> is a universal asynchronous receiver-transmitter (UART) module that provides the receiving and transmitting circuits required for serial communication for both the serial port <b>180</b> and the infrared port <b>64</b>. Communication circuitry <b>420</b> also includes digital signal processor (DSP) <b>422</b> for processing data to be transmitted or data that are received via transceiver <b>408</b>.
0044Also included in computer system <b>100</b> is an optional alphanumeric input device <b>106</b> that, in one implementation, is a handwriting recognition pad (“digitizer”). Alphanumeric input device <b>106</b> can communicate information and command selections to main processor <b>450</b> via bus <b>300</b>. In one implementation, alphanumeric input device <b>106</b> is a touch screen device. Alphanumeric input device <b>460</b> is capable of registering a position where a stylus element (not shown) makes contact.
0045Portable computer system <b>100</b> also includes an optional cursor control or directing device (on-screen cursor control <b>480</b>) coupled to bus <b>300</b> for communicating user input information and command selections to main processor <b>450</b>. In one implementation, on-screen cursor control device <b>480</b> is a touch screen device incorporated with display device <b>105</b>. On-screen cursor control device <b>480</b> is capable of registering a position on display device <b>105</b> where a stylus element makes contact. The display device <b>105</b> utilized with portable computer system <b>100</b> may be a liquid crystal display (LCD) device, a cathode ray tube (CRT), a field emission display device (also called a flat panel CRT), or other display device suitable for generating graphic images and alphanumeric characters recognizable to the user. In the preferred embodiment, display device <b>105</b> is a flat panel display.
0046DSP Control of Multi-Channel Scan for Re-Establishing Connections
0047<figref idref="DRAWINGS">FIG. 5</figref> is a flowchart of the steps in a process <b>500</b> for establishing a wireless connection between portable computer system <b>100</b> (<figref idref="DRAWINGS">FIG. 4</figref>) and a wireless network <b>50</b> (<figref idref="DRAWINGS">FIG. 1</figref>) in accordance with one embodiment of the present invention. In the present embodiment, process <b>500</b> is implemented as computer-readable program instructions executed by portable computer system <b>100</b>. Significantly, to conserve power, aspects of process <b>500</b> are performed by DSP <b>422</b> (<figref idref="DRAWINGS">FIG. 4</figref>) while main processor <b>450</b> is in a sleep mode, as will be seen.
0048In step <b>505</b> of <figref idref="DRAWINGS">FIG. 5</figref>, with reference also to <figref idref="DRAWINGS">FIG. 4</figref>, the main processor <b>450</b> enters a low power mode (e.g., a sleep mode or deep sleep mode) in a conventional manner. In accordance with the present invention, main processor <b>450</b> remains in the sleep mode through step <b>530</b> of process <b>500</b>.
0049In step <b>510</b> of <figref idref="DRAWINGS">FIG. 5</figref>, with reference also to <figref idref="DRAWINGS">FIG. 4</figref>, the method and system of the present invention is automatically initiated based on a triggering event. In essence, a triggering event is an indication that portable computer system <b>100</b> is out of coverage. In one embodiment, the out of coverage event is defined by the Mobitex specification. In this embodiment, an out of coverage event occurs when portable computer system <b>100</b> is unable to acquire a broadcast channel when portable computer system <b>100</b> is powered on (at startup). An out of coverage event can also be triggered when portable computer system <b>100</b> transmits information to base station <b>32</b> (<figref idref="DRAWINGS">FIG. 1A</figref>) and does not receive an acknowledgment signal in return. Also, an out of coverage event can occur when portable computer system <b>100</b> does not receive a transmission from network <b>50</b> (<figref idref="DRAWINGS">FIG. 1A</figref>) for a specified period of time. It is appreciated that there may be other types of triggering events. It is also appreciated that a user of portable computer system <b>100</b> may manually initiate process <b>500</b>.
0050In step <b>515</b> of <figref idref="DRAWINGS">FIG. 5</figref>, again with also reference to <figref idref="DRAWINGS">FIG. 4</figref>, DSP <b>422</b> receives a command to begin the process of multi-channel scans. The command can be received from, for example, the operating system or protocol stack of portable computer system <b>100</b>. The purpose of the multi-channel scan is to allow DSP <b>422</b> to identify those broadcast channels that are strong enough to be used for a wireless connection. As will be seen, DSP <b>422</b> compiles the channels that can be used for the wireless connection into a list that is subsequently forwarded to main processor <b>450</b>.
0051Thus, in accordance with the present invention, DSP <b>422</b>, not main processor <b>450</b>, directs the process of scanning the broadcast channels used by the wireless communication network (e.g., network <b>50</b> of FIG. <b>2</b>), without the involvement of the protocol stack. Therefore, main processor <b>450</b> can remain in the sleep mode, and only DSP <b>422</b> needs to stay up to direct the scans. As a result, less power is consumed, increasing battery life and reducing the frequency at which batteries need to be replaced or recharged.
0052The channels used by the wireless communication network are known; in one embodiment, the channels are specified by the Mobitex specification. In the present embodiment, DSP <b>422</b> directs the scanning of all channels. However, in one embodiment, DSP <b>422</b> ignores certain channels during the scan. For example, interfering sources can add energy (e.g., noise) to certain channels; these channels are known and therefore can be identified to DSP <b>422</b> in advance of the scan. DSP <b>422</b> may then skip these channels during the scan, or DSP <b>422</b> may disregard these channels in the process of identifying channels strong enough to be used for the wireless connection. Thus, DSP <b>422</b> is prevented from incorrectly deducing that a proper signal is being received over those channels when in fact only noise or other interference is being received.
0053In step <b>520</b> of <figref idref="DRAWINGS">FIG. 5</figref>, DSP <b>422</b> of <figref idref="DRAWINGS">FIG. 4</figref> determines which broadcast channels will be acceptable for the wireless connection. In one embodiment, DSP <b>422</b> accomplishes this by comparing a measure of signal strength to a threshold value. In one embodiment, the measure of signal strength is the RF energy or RSSI (receiver signal strength indicator) of the signal received over a channel. In this embodiment, DSP <b>422</b> compares the RF energy or RSSI to the threshold value. If the measure of signal strength is equal to or greater than the threshold value, then the channel is an acceptable candidate and may be used for the wireless connection. If the measure of signal strength is less than the threshold value, than the channel is not an acceptable candidate. It is appreciated that other measures of signal strength and methods other than comparing to a threshold value may be used to identify acceptable broadcast channels in accordance with the present invention.
0054In step <b>525</b> of <figref idref="DRAWINGS">FIG. 5</figref>, if no acceptable broadcast channels are found, process <b>500</b> returns to step <b>515</b>. In this case, after a predefined interval of time has passed, DSP <b>422</b> (<figref idref="DRAWINGS">FIG. 4</figref>) repeats steps <b>515</b> and <b>520</b> until an acceptable channel is found. In one embodiment, DSP <b>422</b> also enters into a sleep mode during the interval of time before steps <b>515</b> and <b>520</b> are repeated.
0055Step <b>530</b> of <figref idref="DRAWINGS">FIG. 5</figref> addresses the case in which DSP <b>422</b> (<figref idref="DRAWINGS">FIG. 4</figref>) has found at least one acceptable channel. When more than one channel has been found, DSP <b>422</b> compiles a list of acceptable channels. In one embodiment, DSP <b>422</b> sorts the list of channels according to each channel's relative signal strength, based on the measure of signal strength determined in step <b>520</b> above.
0056In step <b>535</b> of <figref idref="DRAWINGS">FIG. 5</figref>, with reference also to <figref idref="DRAWINGS">FIG. 4</figref>, DSP <b>422</b> wakes up main processor <b>450</b> and provides to main processor <b>450</b> the list of broadcast channels that can be used to establish a wireless connection. Thus, in accordance with the present invention, main processor <b>450</b> remains in the sleep mode until DSP <b>422</b> finds at least one acceptable broadcast channel. In other words, main processor <b>450</b> is not awakened until preparations for a wireless connection are complete, thereby conserving power and extending battery life.
0057In step <b>540</b> of <figref idref="DRAWINGS">FIG. 5</figref>, main processor <b>450</b> (<figref idref="DRAWINGS">FIG. 4</figref>) establishes the wireless connection to the wireless network (e.g., network <b>50</b> of <figref idref="DRAWINGS">FIG. 2</figref>) using known protocols, such as those described by the Mobitex specification. In one embodiment, main processor <b>450</b> uses the broadcast channel having the highest measure of signal strength as determined in step <b>520</b> above. Subsequently, main processor <b>450</b> can then return to the sleep mode, and portable computer system <b>100</b> enters the in-coverage mode in which it periodically checks for transmissions over the wireless connection now established.
0058In summary, the present invention provides a method and system that reduce the power needed for establishing a wireless connection when an existing connection is lost or when a broadcast channel cannot be acquired. In accordance with the present invention, the DSP implements a process for performing multi-channel scans without waking the main processor. Therefore, only the DSP needs to stay up to direct the scans. Not until the DSP determines that the portable computer system can be placed into coverage, or the user tries to perform an over-the-air operation manually, is the main processor awakened. This stops the deep sleep process and returns control to the protocol stack in the main processor. The main processor can then establish the wireless connection and place the portable computer system back into the in-coverage mode of operation. With the main processor remaining in a low power mode while the DSP performs the multi-channel scan, power is conserved, prolonging the battery life of the portable computer system (that is, batteries do not have to changed or charged as frequently).
0059The present invention has been described in the context of a portable computer system; however, the present invention may also be implemented in other types of devices having, for example, a main processor and a DSP, such that the main processor is placed in or remains in a low power mode while the DSP performs certain functions on behalf of the processor. Furthermore, it is appreciated that these certain functions may include functions other than those associated with establishing (or re-establishing) wireless connections.
0060The preferred embodiment of the present invention, direct DSP control of multi-channel scan for re-establishing connections in a wirelessly networked device, is thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.
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Numbers
- Publication
- 06901276
- Publication, DOCDB
- 6901276
- Publication, EPODOC
- US6901276
- Application
- 9847768
- Application, DOCDB
- 84776801
- Application, EPODOC
- US20010847768
Titles
- English
- Direct digital signal processor control of multi-channel scan for re-establishing connections in a wirelessly networked device
Patent term adjustment
- A delay
- +729 daysthe office missed an examination deadline
- Applicant delay
- −49 days
- Net adjustment
- 680 days
Classification
- CPC, 6
- H04W52/0209
- H04W48/16
- H04W76/19
- H04W52/0245
- Y02D30/70
- H04W72/30
- IPC, 3
- H04B1 16
- H04W48 16
- H04W52 02
- USPC, 4
- 455574000
- 370311000
- 455343200
- 455515000